In terms of the impact of this deal on Pan Am, I think the tweet by Mr. Fink is telling- it'll be small for Pan Am, and, given the nature of international container transportation economics, will likely not lead to a game-changer over the long run. But, it's political in nature, trumpeting job creation and justifying public investment in the port.
It's gonna be tough for Pan Am to participate in a sizable share of this container traffic: it's small volume unevenly distributed due to the bi-monthly sailings with resulting connectivity challenges to/from the 4 potential Class 1 outlets, creating cost and service implications which will make it hard to compete with direct trucking or trucking to the railheads in Auburn, Ayer or Worcester.
Though it's exciting for and benefits Portland and Maine to some degree, it will not lead to Portland becoming a large, meaningful container port that will generate sizable rail volume moving forward. Large-scale International container transporation is driven by the economics of minimizing port calls to maximize ship productivity in concert with ports that minimize inland transportation costs by being closest to the largest (coastal and inland) consumption points. Unfortunately, this does not favor Portland and I don't see anything on the horizon that would change this, allowing Portland to break out of serving a small niche and generate sizable rail international container traffic.